GRANITIC AND ASSOCIATED ROCKS. 633 
material, while in others both the green and red rocks are associated, 
showing, by their gradations, the close relation between the jasper and 
the prase rock. 
A variety resembling bloodstone is also met with at times; it has 
a dark rich green colour and jasper-like fracture, though no specimens 
were seen with the red spots of true bloodstone. 
From the transitions here pointed out, it appears that the jasper and 
prase rocks are closely connected with the talcose series; and that the 
translucent prases and bloodstones here found are only varieties of 
its condition. 
A chloritic rock occurs on the northern declivities of the Umpqua 
Mountains, closely associated with the talcose varieties, and forming 
part of the same series. It is a granular olive-green rock, and is 
speckled white with feldspar. It resembles some greenstones. It is 
rather soft, and breaks readily with a rough surface. Isolated masses 
of foliated chlorite sometimes occur in this rock, and are generally 
associated with interlaminations of quartz. A prasoid variety in the 
same region has a light grayish-green colour, compact texture, and 
smooth fracture, and contains disseminated grains of quartz. The 
quartz may be seen gradually disappearing or blending with the mass, 
and the transition may thus be traced to a green jasper or prase. 
No granular steatite of good quality was observed in place. An 
imperfect soapstone was occasionally met with, and fragments of a 
purer kind occur in the Shasty Mountains, leaving little doubt that 
large beds may yet be discovered. ‘These fragments were of a gray- 
ish-green colour, and had the usual characters of this rock. On the 
north shores of the bay of San Francisco, near the prominent point in 
the straits, just east of Sansalito Harbour, there is a steatitic rock in- 
termediate between true steatite and laminated talc. It is a fragile, 
soapy rock, breaking irregularly into curved or lenticular lamine, 
apparently indicating an approach to a concentric structure. The 
colour is gray or grayish-green, sometimes mottled with darker shades 
of green. Round and semi-angular masses of a dark green rock, re- 
sembling serpentine, are imbedded in the bank of tale rock ; they are 
harder than ordinary serpentine, yet have the same features and frac- 
ture. Large portions of the bank, in some places, consist of this im- 
pure serpentine. The tale rock near by on the same shores passes 
into a talcose slate, very evenly fissile. The slates have the greasy 
feel of talc, and are of various colours, as white, gray, green, brown 
and dull black; they have a speckled appearance owing to the disse- 
159 
